ABSTRACT
Cyclohexane is present in very small quantities, ranging from 0.05 to 1.0%, in crude oil. The routes to nylon 66 and to nylon 6 both start from cyclohexane. Over 90% of cyclohexane is produced by the hydrogenation of benzene. Benzene and hydrogen are fed cold into a reactor, containing a catalyst consisting of finely-divided Raney nickel in liquid cyclohexane. The purity of the resultant cyclohexane depends on the purity of the benzene feed. Recovery of cyclohexane from naphtha is difficult because its boiling point is so similar to those of a number of other hydrocarbons and hexanes as well as methylcyclopentane and benzene. Naphtha is fractionated to remove methylcyclopentane and to concentrate the cyclohexane to give a purity of 85%. Cyclohexane vapour readily forms explosive mixtures in air with flashback a great hazard to firefighters. Handling cyclohexane involves the same flammability risks as for other similarly volatile saturated hydrocarbons.
